Mucin hypersecretion is a feature common to a variety of airway diseases associated with airway inflammation. Airway epithelial cells respond to a variety of proinflammatory cytokines with an increase in mucin secretion. Human airway epithelial cells express products of at least seven mucin genes. Ribonuclease protection assays have been developed for the quantitation of steady-state mRNA levels of mucin gene in airway epithelial cells in culture. Analysis of changes in steady-state mRNA levels of at least six of these genes in response to proinflammatory mediators and to changes in intracellular second messengers is in progress.